Off-flavour development in soybeans: comparative role of some antioxidants and related enzymes

Off-flavour development is the major impediment in the effective use of soybeans as food ingredients. In the present study, the levels of vitamin E and vitamin C along with those of antioxidant enzymes, like superoxide dismutase, peroxidase and catalase, were estimated in sixteen soybean varieties to explore their effectiveness against off-flavour generation. Thiobarbituric acid (TBA) number, an indicator of lipid peroxidation, was used to measure the quality with respect to off-flavour. Data on activities of various antioxidant enzymes indicated that the off-flavour is mainly generated enzymatically by the action of lipoxygenase on polyunsaturated fatty acids. Furthermore, varieties PK 416 and JS 7105 had the highest level of vitamin E while their TBA number was the lowest indicating the inverse relationship between the two parameters. It was further observed that the peroxidative effect of higher vitamin C concentrations is controlled by vitamin E. Among the varieties analyzed, PK 416 and JS 7105 appeared to have greater potential as most acceptable food ingredients.